Fruit-flies go to space!

[scicop]

http://www.cnn.com/2006/TECH/space/07/17/shuttle.flies/index.html

 

With the goal of understanding the contribution of gravity to the developing/matured immune system, NASA scientist sent up some drosophila eggs on the recent Discovery mission. Hatched in space, they will now be studied at NASA.

 

I should note the Drosophilia shares an immune system similar to our own innate-immune system. Innate immunity in mammals is hallmarked by the presence of antigen sensing receptors called Toll-like Receptors (TLRs), humans have 10 of them with differing antigen molecule selectivity. TLRs namesake is derived from the Drosophila TLR ortholog "Toll" which has been shown to participate in both development and antigen sensing with respect to fungal infection.

 

So anyway, I guess one day NASA will have an opening for a drosophila geneticist/mission specialist to go up in space! Fly-folks..get your applications in!

 

So anyway..anyone have some good ideas regarding biological based experiments to be done in space?

 

I have one...how about assessing long-term impact (over 1 month) of low/absent gravity on the rate of CNS neurogensis OR rate of new blood derived stem-cell formation in adult rats/mice as a means to study say....lack of gravity induced muscle atrophy?

[Mokele]

Personally, I strongly suspect this experiment, and any others at the cellular level, which show precisely nothing.

 

A fundamental rule of biological scaling in fluid systems is that for small things, viscous forces predominate, while for big things, inertial forces predominate. A spiderling can fly by just letting out a strand of silk, which increases it's surface area enough that viscous forces predominate and it moves like dust in the wind, while birds must rely on active exertion against the fluid to keep from falling. The mechanism behind the sort of cellular-level effects in development is usually the diffusion of signaling molecules, which are *tiny*.

 

Essentially, anything where the moving parts are microscopic will show no effect, for precisely the same reason that plankton float: at that scale, the effect of gavity is miniscule compared to the effect of fluid forces like internal currents.

 

There are potential experiments in my field (organismal biomechanics) where reduced gravity or microgravity could be useful, but such experiments would also be limited by the animal's behavior (not to mention the feasability of getting them into orbit and caring for them). Plus, there's the issue of how useful such an artificial state is in determining what happens naturally.

 

Mokele

[Dr. Dalek]

Plus, there's the issue of how useful such an artificial state is in determining what happens naturally.

 

The experiment may just be for the purposes of pure knowlage. Knowlage of how, or if, body chemistry is effected by microgravity could be useful in the future. Wouldn't you agree?

[Mokele]

It's not the pure knowledge aspect (everything I do is pure knowledge), but rather that we can't be sure what we're seeing has value. For instance, if I was seeing how snakes attempt to move in zero-g, I would be unable to distinguish whether their reactions were due to confusion when faced with a system they've never dealt with, or due to genuine mechanical properties of the snake's muscular system.

 

It all depends on the point of the specific experiment. Some experiments are such that you can place the system in highly artificial situations and still have useful knowledge, while in other cases, the behavior of a system in highly artifical or unusual conditions might reveal little or nothing about how the system works. It's all dependent upon the system and the question you're trying to answer.

 

Personally, I tend to be critical of 'gee-whiz science', where the experiment is basically to see what happens under X weird conditions, with no real larger purpose. Not that serendipitous discoveries cannot be made that way, but rather that the chances of meaningful discoveries are much lower.

 

Mokele

[Dr. Dalek]

Personally, I tend to be critical of 'gee-whiz science', where the experiment is basically to see what happens under X weird conditions, with no real larger purpose. Not that serendipitous discoveries cannot be made that way, but rather that the chances of meaningful discoveries are much lower.

You can't expect all experiments to yeild meaningful results. However simple and obviously flawed experiments can become the basis for future ones, as the scientists get a feel and understanding of what works and what dosn't.

Forgive the cliche, but space is "A new fronteir." Untill the first launching of space craft almost half a century ago, experiments on biology have been limited to the ground. Observing the way normal phenominon and biological processes occure in space could be importent to the future of NASA.

This experiment might seem alittle pointless, however in terms of science you always have to start somewhere. After all "heros" of science, such as Newton, and Darwin, were not actually scientists. They were natural philosophers. It wasn't untill they created a foundation of knowlage and understanding that science as we know it could be built up.

[scicop]

The one thing all experiments have in common here on earth is gravity! Can't assume that things will work the same in a gravity less environment. While your idea of "diffusion" in small spaces would be conserve may be true on earth, and some developmental processes require "gravitational forces" to set-up gradients and organizers. You can't assume that develomental or even maintanance of certain "molecular" states will be the same in space!!!! would be REAL DUMB!! That is why we do experiments, to test assumptions and hypothesises!

 

Furthermore, those experiments are of complete relevance, not only to help us understand the biological limitations of space travel, but also uderstand what goes on here on earth.

 

My graduate school has a relationship with NASA, they are involved in neuroscience related projects (they are still processing data from the neurolab mission), and as a result I had the pleasure of attending a lecture (and having lunch) by one of the specialist on aboard the neurolab mission (STS-90), a Jay Buckley MD. From his lecture and our conversation, we were exposed to some really neat data that showed in impact of gravity on a number of nervous system functions, including development and ability to maintain a variety of physiological homeostatic states.

 

But don't take my word for, a simple pub-med such of gravity and development will give you alot of hits..expecially in topics that are of a "molecular" nature!

 

So, I think it really dumb to assume the biological functions, even at the molecular level, would be the same in space, as so many publications out there suggest that the lack of (or too much) can have some big (as well as subtle) effects that can be impacting to prolonged human existance in space.

[Mokele]

You can't expect all experiments to yeild meaningful results. However simple and obviously flawed experiments can become the basis for future ones, as the scientists get a feel and understanding of what works and what dosn't.

 

It's not that I think all such experiments are worthless. It's that I don't see an a priori reason to expect them to yield results.

 

It's like me testing the locomotor differences between a corn snake and a black rat snake. They're from the same genus, probably very closely related within that genus, appear very similar, half similar morphology and a similar niche. There's no reason to expect their locomotion to differ in any way beyond the effects of size. Even if there is some difference, it's likely to be so tiny that I'd need thousands of experiments to detect it.

 

What I'm saying is that if you don't have a reason to expect significant results, you're very likely just wasting your time. Sure, you might find something, but 99.99% of the time you won't. That's why hypotheses are so important: you need a good reason to do it (alternatively, you need to give your granting agency a good reason to give you money to do it) and a reason why anyone should even care and treat it as more than trivia.

 

Can't assume that things will work the same in a gravity less environment. While your idea of "diffusion" in small spaces would be conserve may be true on earth, and some developmental processes require "gravitational forces" to set-up gradients and organizers. You can't assume that develomental or even maintanance of certain "molecular" states will be the same in space!!!! would be REAL DUMB!! That is why we do experiments, to test assumptions and hypothesises!

 

You can if gravity is a negligible force on the system. That's like saying that all electronics experiments have been conducted in a nitrogen atmosphere, so we don't know what'll happen if we replace that with argon: there's no good reason to expect it to make a difference.

 

Same thing here: in fluid system, the smaller you get, the less important gravity is and the more important fluid forces are. Look at a vial of blood. There's white blood cells, reb blood cells, platelets, and plasma in there, and each of those has a different weight and density. But if you leave blood out (and prevent clotting), it won't separate. The only way to separate the components is to centrifuge them, which effectively massively increases the gravitational force so that it can overpower the fluid forces. Note: gravity only has a major effect on cells in a fluid when it's artificially increased to far beyond the normal level. Now, signaling molecules are a *lot* smaller, yet you see to expect this basic physics to not hold true for them. Why?

 

they are involved in neuroscience related projects (they are still processing data from the neurolab mission), and as a result I had the pleasure of attending a lecture (and having lunch) by one of the specialist on aboard the neurolab mission (STS-90), a Jay Buckley MD. From his lecture and our conversation, we were exposed to some really neat data that showed in impact of gravity on a number of nervous system functions, including development and ability to maintain a variety of physiological homeostatic states.

 

Did they control for radiation? There's an *assload* of radiation out there, and that could also produce effects.

 

I'm not just trying to be difficult. The relative importance for fluid vs gravitational forces on organisms as their size changes is important, well-known, and well-tested biomechanics. I need to see some very good reasoning on why this principle does not apply in relationship to cellular signaling and other molecular processes.

 

But don't take my word for, a simple pub-med such of gravity and development will give you alot of hits..expecially in topics that are of a "molecular" nature!

 

I just did. The very first paper I found on the topic was about frog embryos, all of which were nearly normal and only showed transient abnormalities (which may be due to the radiation in space).

 

So, I think it really dumb to assume the biological functions, even at the molecular level, would be the same in space, as so many publications out there suggest that the lack of (or too much) can have some big (as well as subtle) effects that can be impacting to prolonged human existance in space.

 

Read. My. Post.

 

I am not *assuming* anything. I am stating that, based on *KNOWN* and *WELL-STUDIED* biomechanical and physical principles, there is a strong a priori reason to suspect that no difference would be evident in most molecular systems.

 

Try reading posts and actually comprehending them. It helps.

 

Mokele

[ecoli]

You raise interesting points that I wouldn't have thought to consider before. Thank you.

[CharonY]

That's actually a good example of a typical non-hypothesis driven approach that are en vogue again lately. Kind of similar to many high-throughput (but low output ) "systems biology" approaches that are running wild nowadays.

What irks me a little is the money that goes into these approaches. Not that I really may complain, a part of my PhD work was funded by it (although I used it differently than I was supposed to, ah well).

Anyhow as can be seen, I share Mokele's sentiments regarding the NASA experiments. They are porbably also more used as a side-aspect with which they want to spread interest into other fields. The technical necessities for full-fledged meaningful microgravity experiments done in space are probably too high to actually perform them.

[scicop]

Well, I would rather see the space experiments funded anyday rather that some of the questionable research being funded here on earth!

 

It doesn't matter if nothing may come out of the research, its still data! I've done alot of experiments where I did not obtained ground-breaking results, but it was still data! So even if I found that Beta-arrestin can associate with one receptor subtype and that it could associate no-differently with another "related" subtype, its still data that no one else has published or reported! I may not have been able to publish it, but at I did get the word out through conferences and word of mouth with fellow colleagues in the field (who were grateful for the knowledge, because they were going down the same path!).

 

Back to space, the fact that astronauts who have been in space for prolong periods show symptoms muscle/nervous system atrophy as well as vestibular dysfunction that can persists for weeks after their return to earth does suggest changes in physiology in response to weightlessness (lack of gravational stimuli or microgravity stimuli I guess). These are all mediated by molecular changes that mediate neurotransmission or neuroplasticity or muscle degeneration. I see nothing wrong in trying to elucidate the "space mediated" mechanism of these pathologies (yes..pathologies...albeit repairable) Whereas I don't argue your fluid dynamics/forces statement at all, its never good to assume things will be the same from place to place!

 

As for radiation, yeah of course, you can't control for that in space, but perhaps we can control for it on earth by mimicing radiation exposure on earth for similar experiments? Maybe that's what they'll be looking for in the Drosophila flies?? Maybe they are looking at P-element (or transposon) jumping as it relates to the expression of immune-system genes???? We don't know the full details of the experiments do we? Do for now, I'm just assuming.

 

(by they way...that's how we trigger P-element jumping here on earth, we expose fruit-flys to doses of X-ray radiation..i did it to "knock-out" or rather inactivate a nearby gene...lot of crosses after-wards ....lots of crosses to get one!!"

 

Of course I'm not thinking safety issues here, but just a thought.

[Mokele]

Well, I would rather see the space experiments funded anyday rather that some of the questionable research being funded here on earth!

 

I would rather see *no* questionable research funded. Nothing where there isn't an a-priori hypothesis-driven reason to expect something. This is science, not an episode of Mr. Wizard. If other people don't have their hypotheses sorted out, give me the money, I've got loads of testable hypotheses with a-priori expectations to back them up.

 

Back to space, the fact that astronauts who have been in space for prolong periods show symptoms muscle/nervous system atrophy as well as vestibular dysfunction that can persists for weeks after their return to earth does suggest changes in physiology in response to weightlessness (lack of gravational stimuli or microgravity stimuli I guess). These are all mediated by molecular changes that mediate neurotransmission or neuroplasticity or muscle degeneration. I see nothing wrong in trying to elucidate the "space mediated" mechanism of these pathologies (yes..pathologies...albeit repairable)

 

Those, however, are at the *systems* level, not the cellular level. Lack of force to work against results in muscular atrophy, and possibly also atrophy of associate nerves. It's obvious why there's vestibular problems too. All of these could have been (and likely were) predicted prior to long-term stays in space simply from our knowledge of biology and physics.

 

Whereas I don't argue your fluid dynamics/forces statement at all, its never good to assume things will be the same from place to place!

 

So, why do we assume that physics works the same on Mars? We've never been there, so we can't be sure. How do we even know gravity works there, as opposed to some strange and mysterious other force? We don't. But we have no a priori reason to expect there to be a difference.

 

We assume things alll the time, in all the sciences. You assume that bacteria in a culture won't be terribly different from those in a patient's gut, I assume that because the force measurement plate is flush with the ground and immovable, it won't affect the animal's walking significantly.

 

The important thing is that without these assumptions we'd waste 99% of our time chasing dead-end, unlikely possibilities. The key is not in the assumptions, but knowing the reasoning behind them and what situations are likely to violate them. If there's no a-priori reason to expect the assumption to be violated, why bother?

 

Is it foolish of me to just assume that the gravitation force on an item is the same in my animal care room as the experimental room next door? There's no a priori reason to expect a difference, but you seem to endorse a position which would leave me testing the gravitational acceleration in both rooms for no good reason.

 

As for radiation, yeah of course, you can't control for that in space, but perhaps we can control for it on earth by mimicing radiation exposure on earth for similar experiments? Maybe that's what they'll be looking for in the Drosophila flies??

 

Then why not irradiate them here, on earth, and save some $ for other grants to other scientists? There's an a priori reason to expect radiation to have an effect, but no reason to expect an effect of gravity.

 

Mokele

[ed84c]

This is nothing new, infact fruit flies were the first organisms purpousely sent into space.

[Steph]

The point of these experiments is that, people will hear : "Flies in space" and go "wow this is pretty cool". this will look as if NASA is doing something important (although incomprehensible to them). This conversation that we have now is the proof of that. Its useless for science, but great for PR.

[Dr. Dalek]

The point of these experiments is that, people will hear : "Flies in space" and go "wow this is pretty cool". this will look as if NASA is doing something important (although incomprehensible to them). This conversation that we have now is the proof of that. Its useless for science, but great for PR.

Right, they should be more focused on replacing these aging space shuttles, not to mention that whole foam thing.

[Igor Suman]

So anyway..anyone have some good ideas regarding biological based experiments to be done in space?

 

I have one...how about assessing long-term impact (over 1 month) of low/absent gravity on the rate of CNS neurogensis OR rate of new blood derived stem-cell formation in adult rats/mice as a means to study say....lack of gravity induced muscle atrophy?

 

We will soon find out how rodents cope in space:-

 

" In 2006 a group of mice-astronauts will orbit Earth inside a spinning spacecraft.

Their mission: to learn what its like to live on Mars."

http://science.nasa.gov/headlines/y2004/20jan_marsmice.htm

 

In space no-one can hear you squeak